The present invention relates to canisters for adsorbing and desorbing vapor generated from fuel systems of engines in motor vehicles, etc.
Japanese Laid-Open Patent Publication No. 2000-186635 in the name of the applicant of this application discloses a canister. This canister has an adsorbent housed in an adsorbent chamber, a filter provided between the adsorbent chamber and a port provided on an end wall of the adsorbent chamber. The filter is welded on the end wall of the adsorbent chamber.
In sequence steps for mounting the filter on a canister case in the known canister, after the filter is provided in the adsorbent chamber, the filter is welded on the end wall of the adsorbent chamber. The filter is loosely fitted in the adsorbent chamber in order to facilitate proper installation of the filter in the adsorbent chamber. Thus, the filter is free between the time the filter is provided in the adsorbent chamber and the time the filter is welded, so that there is a case that the filter is lifted due to static electricity or the like and is unintentionally displaced. When the filter is displaced, failure in filter assembly may be caused, or complex management in automated lines is required. It is not preferred that when the failure in the filter assembly is severe, the adsorbent spills into the port. In addition, it is thought that displacement can be prevented by press fitting the filter in the adsorbent chamber, however a circumferential edge of the filter may turn up, and the edge turned up could cause problems in an assembly step, so that such press fitting is not preferred.
Therefore, there has been a need for improved canisters capable of preventing displacement of the filter between the time the filter is located and the time the filter is welded.